Ticket #4286 - PartDesign hole: angle of the tapered hole does not match the tapered angle specified

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matimat
Posts: 5
Joined: Tue Mar 10, 2020 4:29 pm

Ticket #4286 - PartDesign hole: angle of the tapered hole does not match the tapered angle specified

Post by matimat »

when I create a tapered hole with the Partdesign hole tool, the angle of the tapered hole does not match the tapered angle specified in the tool.

an example: if I place a tapered hole with a specified taper angle of 120° in a cylinder created with Part, the hole is executed with an angle of 116.57°. For very small angles, the executed and specified taper angles are almost identical, for large angles the deviations become very large.
tapered_angle-120degree.png
tapered_angle-120degree.png (69.01 KiB) Viewed 749 times
The executed and the specified angle are related by: 116.57 = 90 - ARCTAN(COS(120))
The formula also holds for other pairs.

As a workaround to set the executed angle directly, I tried this relation in the form: tapered_angle_to_be_specified = ARCCOS(TAN(90 - tapered_angle_to_be_executed))
tapered_angle-125degree.png
tapered_angle-125degree.png (74.6 KiB) Viewed 749 times
This worked for me so far.


OS: macOS 10.14
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16146 (Git)
Build type: Release
Branch: (HEAD detached at 0.18.4)
Hash: 980bf9060e28555fecd9e3462f68ca74007b70f8
Python version: 3.6.7
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: German/Germany (de_DE)

I also tried it with similar results with v18.2 as well as v19.pre
Attachments
PartDesign-tapered-hole-feature.FCStd
(13.57 KiB) Downloaded 19 times
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Kunda1
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Re: PartDesign hole: angle of the tapered hole does not match the tapered angle specified

Post by Kunda1 »

rynn wrote: Wed Mar 11, 2020 2:49 pm for a (quick) patch see: https://forum.freecadweb.org/viewtopic. ... 56#p375915
I'm confused, is this the proposed fix for issue #4286 ?
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rynn
Posts: 454
Joined: Tue Jul 31, 2018 7:00 am

Re: PartDesign hole: angle of the tapered hole does not match the tapered angle specified

Post by rynn »

Kunda1 wrote: Wed Mar 11, 2020 5:03 pm I'm confused, is this the proposed fix for issue #4286 ?
If I haven’t mixed up something: Yep.
chrisb
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Re: PartDesign hole: angle of the tapered hole does not match the tapered angle specified

Post by chrisb »

Kunda1 wrote: Wed Mar 11, 2020 5:03 pm I'm confused, is this the proposed fix for issue #4286 ?
So it seems. Is there a pull request?
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